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My girlfriend has lupus, and also had a stroke in 2017. She's just 24 now. After the stroke, she was placed on warfarin. The warfarin levels have to be continuously adjusted to whatever her PT-INR level is.

She's had a nasty cough/congestion over the last couple of months and was diagnosed with pneumonia. A whooping cough test was done at a local hospital three weeks ago, which had to be set to a major medical facility in Charlotte because the local systems cannot diagnose it. Due to her lupus, she also has significant nausea.

She was prescribed dextromethorphan and phenergan cough syrup for the cough/nausea, but continued to take the warfarin, which has caused a feedback loop on her PT-INR. Her PT-INR was measured at 18 at the hospital. Her home machine stops at 7 - anything at 8 or above throws an error message. 2-3 is therapeutic to her.

It looks like this feedback loop caused her PT-INR to go haywire. The GP didn't watch the meds. The pharmacist didn't. They've now prescribed heavy Vitamin K doses and are telling her to eat tons of greens to help the clotting process to keep the PT-INR down.

If it's not down to 8 by tomorrow, she'll be admitted to a hospital need one of us like, but which is close to our homes. Who should be keeping tabs on these drugs? Her, the physician, pharmacist? This just seems like negligence all around!

My girlfriend has lupus, and also had a stroke in 2017. She's just 24 now. After the stroke, she was placed on warfarin. The warfarin levels have to be continuously adjusted to whatever her PT-INR level is.

She's had a nasty cough/congestion over the last couple of months and was diagnosed with pneumonia. A whooping cough test was done at a local hospital three weeks ago, which had to be set to a major medical facility in Charlotte because the local systems cannot diagnose it. Due to her lupus, she also has significant nausea.

She was prescribed dextromethorphan and phenergan cough syrup for the cough/nausea, but continued to take the warfarin, which has caused a feedback loop on her PT-INR. Her PT-INR was measured at 18 at the hospital. Her home machine stops at 7 - anything at 8 or above throws an error message. 2-3 is therapeutic to her.

It looks like this feedback loop caused her PT-INR to go haywire. The GP didn't watch the meds. The pharmacist didn't. They've now prescribed heavy Vitamin K doses and are telling her to eat tons of greens to help the clotting process to keep the PT-INR down.

If it's not down to 8 by tomorrow, she'll be admitted to a hospital need one of us like, but which is close to our homes. Who should be keeping tabs on these drugs? Her, the physician, pharmacist? This just seems like negligence all around!

It's not really a "feedback loop". The dextromethorphan and phenergan affect levels of enzymes that break the warfarin down. The levels of those enzymes are also genetically determined, and it is likely that your GF makes less of them than some people do. It is something that can be tested for. My 23AndMe DNA results show that I would be sensitive to the effect of warfarin and might need lower than average doses.

I am surprised that the pharmacist did not catch that, assuming she gets all of her drugs from one pharmacy, which is something we should all consider doing.

It's not really a "feedback loop". The dextromethorphan and phenergan affect levels of enzymes that break the warfarin down. The levels of those enzymes are also genetically determined, and it is likely that your GF makes less of them than some people do. It is something that can be tested for. My 23AndMe DNA results show that I would be sensitive to the effect of warfarin and might need lower than average doses.

I am surprised that the pharmacist did not catch that, assuming she gets all of her drugs from one pharmacy, which is something we should all consider doing.

Absolutely. A pharmacy can only catch something if they prescribe all the meds. If she got it in an institutional setting that did not have a list of her meds already, they would not know unless the GF told them. Warfarin is a pretty big deal and the GF should make mention of it if she is not sure that the place has the full med list.

My girlfriend has lupus, and also had a stroke in 2017. She's just 24 now. After the stroke, she was placed on warfarin. The warfarin levels have to be continuously adjusted to whatever her PT-INR level is.

She's had a nasty cough/congestion over the last couple of months and was diagnosed with pneumonia. A whooping cough test was done at a local hospital three weeks ago, which had to be set to a major medical facility in Charlotte because the local systems cannot diagnose it. Due to her lupus, she also has significant nausea.

She was prescribed dextromethorphan and phenergan cough syrup for the cough/nausea, but continued to take the warfarin, which has caused a feedback loop on her PT-INR. Her PT-INR was measured at 18 at the hospital. Her home machine stops at 7 - anything at 8 or above throws an error message. 2-3 is therapeutic to her.

It looks like this feedback loop caused her PT-INR to go haywire. The GP didn't watch the meds. The pharmacist didn't. They've now prescribed heavy Vitamin K doses and are telling her to eat tons of greens to help the clotting process to keep the PT-INR down.

If it's not down to 8 by tomorrow, she'll be admitted to a hospital need one of us like, but which is close to our homes. Who should be keeping tabs on these drugs? Her, the physician, pharmacist? This just seems like negligence all around!

All. In the first instance, she needs to tell the physician straight away she is on Warfarin. The Physician may or may not get that from records, depending on whether the records are accurate and depending on patient compliance. She should also tell the physician about any other non-prescribed drugs she is taking, as it would not be possible for the physician to know that (or the pharmacist). The physician should check when prescribing for drug-interactions. Finally, when picking up from the pharmacy the pharmacist will normally ask you if you have any questions about the medication. If you are on a serious-ass drug like warfarin, then there should be questions - is this ok with warfarin? If everyone plays their role in the chain its least likely to occur.

She was prescribed dextromethorphan and phenergan cough syrup for the cough/nausea, but continued to take the warfarin, which has caused a feedback loop on her PT-INR. Her PT-INR was measured at 18 at the hospital. Her home machine stops at 7 - anything at 8 or above throws an error message. 2-3 is therapeutic to her.

There is no D D interaction listed for promethazine (Phenergan), dextromethorphan and warfarin

I ran the combo through 3 professional database interaction checkers

Only warfarin interaction listed with these meds was Vicks DM and the interaction was with the menthol (mechanism unknown)

also, i'm wondering if nausea caused a change in diet. and what was the treatment for pneumonia? some abx. have well documented interactions with warfarin.

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